Rock drill



E. G. GARTIN' Dec. 1, 1936.

ROCK DRILL Original Filed Dec. 22, 1933 n 1TV M H N a N mG m @N A Y 6 BPatented Dec. 1, 1936 UNITED" STATES PATENT QFFIQE ROCK DRILL Elmer G.Gartin,

Massachusetts a corporation of Original application December 22, 1933,Serial Divided and this application August 27, 1934, Serial No. 741,620

2 Claims.

This invention relates to pressure fluid motors, and more particularlyto improvements in the fluid distribution means of a pressure fluidmotor of the pressure fluid actuated, reciprocating hammer piston, type.

An object of this invention is to provide an improved pressure fluidactuated hammer motor of the reciprocating piston type. Yet anotherobject is to provide an improved pressure fluid actuated hammer motorhaving improved valve means for controlling the fluid distribution meanstherefor. These and other objects of the invention will, however,hereinafter more fully appear.

This application is a division of my copending application Serial No.703,580, flled December 22, 1933.

In the accompanying drawing there is shown for purposes of illustrationone form which the invention may assume in practice.

In this drawing,-

Fig. 1 is a mongrel longitudinal section through theillustrative form ofthe improved pressure fluid motor.

Fig. 2 is a view similar to Fig. 1 showing the fluid distributing valveand motor piston in a different position.

In this illustrative construction there is shown a pressure fluid motorof the reciprocating piston, hammer type especially designed for use inrock drills and comprising a motor cylinder l having a bore 2 containinga reciprocable hammer piston 3. The motor cylinder has a front head 4arranged within a bore 5 formed in a chuck housing or frame 6 to whichthe motor cylinder is suitably secured. The motor cylinder is providedwith a rear head block I having secured thereto in non-rotatablerelation with respect thereto a rear head member 8; and the elements 1,4, 6, l and 8 are held in assembled relation in any suitable manner. Thehammer piston 3 is formed with a forwardly projecting striking bar 9guided within a bore 9 formed in the front head l, and this striking baris adapted to transmit the hammer blows of the motor piston to the shankof a suitable working implement it, such as a rock drill steel, suitablysupported within the chuck housing 6.

As is usual in rock drill type pressure fluid motors there is providedmeans operated by the hammer piston for imparting rotative movement tothe working implement If) as the latter is percussively actuated by thepiston striking bar, and this rotation means comprises a spirallygrooved rifle bar H fixed to the non-rotatable head member 8 andprojecting within a bore I2 formed within the motor piston 3, the spiralgrooves of this rifle bar engaging the spiral lugs of a rifle nut I3flxed within the rear end of the motor piston. This rifle bar, due toits spiral interlocking engagement with the hammer piston, causes thelatter to oscillate back and forth as the same reciprocates, and thisoscillatory movement of the motor piston is transformed into anintermittent rotary motion by means of a slip rotation mechanism,generally designated I4, through longitudinal grooves 55 formed on theexterior periphery of the striking bar 9 interlocked with inwardlyprojecting teeth it formed on a combined chuck nut and grip member H, asclearly described in my copending application Serial No, 703,580referred to above. Driven through this slip rotation mechanism M is achuck sleeve 13 rotatably mounted within the chuck housing 6 and havingsecured thereto a chuck bushing i9 within which the shank of the workingimplement ill is supported. It will thus be seen that as the workingimplement is percussively actuated by the motor piston, it is at thesame time intermittently rotated through the rifle bar i l and sliprotation mechanism i l. As this rotation means for the working implementis clearly described in the copending application above referred to, anddoes not enter into this invention other than as regards the particularassociation of the rifle bar with an element of the valve mechanism,further description thereof herein is unnecessary.

Now referring to the improved fluid distribution means for effectingreciprocation oi the motor piston 3, it will be noted that guided on areduced cylindrical portion 29 of the head member 8 and surrounding therear portion of the rifle bar H is a fluid distributing valve 28, hereinin the shape of an annular disc and arranged in an annular valve chamber22 formed in the rear head block I and the head member 3. Arrangedwithin the head block I is a throttle valve 23 having a central fluidsupply passage 2& and controlling, through a radial port 25, the flow ofpressure fluid from the passage 25 to a passage 26 formed in the headblock I and communicating with the valve chamber 22 through an annularchamber El. Formed in the forward face of the member 8 at the rear ofthe valve H is an annular groove 28 connected through a passage 7 29with the fluid supply passage 25. Formed on the head member 8 is anannular groove 30 communicating through passages 33 with the valvechamber at the rear side of the valve, and connected through passages 32and ports 33 with the forward end of the cylinder bore. The valvechamber at the forward side of the valve communicates with the rear endof the cylinder bore through an axial passage 34 formed in the headblock 1 and surrounding the rifle bar ll. Pressure fluid isexhaustedfrom the opposite ends of the cylinder bore under the controlof the motor piston through a central exhaust passage 35. It will benoted that the head block or rear cylinder head I is provided with astepped bore, comprising a rearward bore, providing the valve chamber 22and for most of its length filled by the annularly-grooved cylindricalportion of the head member 3, andfurther comprising a smaller boreproviding the passage 34. The cylindrical guiding portion 20 of themember 8 is within the stepped bore, herein within the larger, rearwardportion thereof. Head block 1 and h ad member 8 may be regarded as mainand supplemental heads.

When the parts are in the position shown in Fig. l the communication ofthe groove 21 with the passages 28, 32 is cut off by the valve 2|, andpressure fluid flows through the passage 26, annular groove 27, throughthe valve chamber 22 past the forward face of the valve and through theaxial passage 34 to the rear end of the cylinder bore to act on the rearpressure area of the piston to drive the latter forwardly to effect itsworking stroke, and as a result delivering a hammer blow to the shank ofthe working implement it When the piston head overruns the exhaustpassage 35, the pressure within the cylinder bore at the rear side ofthe piston head drops 'materially, while the pressure fluid trappedwithin the forward end of the cylinder bore is compressed, and as aresult, the valve 2| is thrown from the position shown in Fig. 1 to theposition shown in Fig. 2, the valve being thrown by the compressionpressure built up within the forward end of the cylinder bore and theconstant pressure in groove 28 acting against the opposing reducedpressure within the rear of the cylinder bore. When the valve is in theposition shown in Fig. 2, against the shoulder at the rearward end ofthe bore or passage 34, the communication of the passage 34 with thevalve chamber is cut oif by the valve 2!, and pressure fluid flows frompassage 25 and annular groove 21 through the valve chamber at the rearside of the valve, through passages 3i, groove 30, passages 32 and ports33 to the forward end of the cylinder bore to act on the forwardpressure area of the motor piston to drive the latter rearwardly toeffect its retraction stroke. As the hammer piston moves rearwardly, theexhaust port 35 is overrun by the front edge of the piston head, therebycausing the pressure of the fluid within the forward end of the cylinderbore to drop materially, while the pressure fluid trapped within therear end of the cylinder bore is compressed, and as a resultgthe valveis thrown from the position shown in 'Fig. 2 back to the position shownin Fig. 1, against an annular seat surface on head member 8, the valvebeing thrown by the compression pressure acting on the forward pressurearea of the valve against the opposing reduced pressure in the groove 28acting on the rear pressure area of the valve. These operations'arerepeated, in rapid succession to effect rapid reciprocation of thehammer piston during normal operation of the motor.

As a result of this invention, it will be noted that an improvedpressure fluid motor of the reciprocating hammer piston type isprovided, especially adapted to use in hammer rock drills havingimproved fluid distribution means. It will further be noted that animproved fluid distribution means is provided for a pressure fluid typemotor, having improved valve means whereby the flow of pressure fluid tothe motor cylinder is controlled in an improved and more effectivemanner. These and other uses and advantages of the improved pressurefluid motor will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and thattheinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a rock drill, a hammer motor including a cylinder having front andrear heads, a piston reciprocable in said cylinder, and fluiddistribution means for effecting reciprocation of said piston includingan axial bore extending through said rear head, a supplemental headsecured to said rear head and having a cylindrical portion fitting saidrear head bore and an integral forward guide projection extendingcentrally within said rear head bore, said guide projection cooperatingWith said rear and supplemental heads to form an annular valve chambersurrounding said guide projection, said rear head providing an annularrearwardly facing valve seat and said supplemental head a forwardlyfacing valve seat, and a disc valve guided on said guide projection andengageable with said valve seats for controlling the flow of pressurefluid to the ends of the motor cylinder, said rear head bore forming alarge axial passage for connecting the forward end of the valve chamberdirectly with the rear end of the motor cylinder in the rearwardposition of said disc valve and said disc valve when seated on saidannular seat cutting off communication of said passage forming borewith. the valve chamber.

2. In a rock drill, a hammer motor including a cylinder having front andrear heads, a piston reciprocable in said cylinder, and fluiddistribution means for effecting reciprocation of said piston includinga stepped bore, comprising alined axial bores of different diameters,extending through said rear head, a supplemental head secured to saidrear head and having a. cylindrical portion fitting the larger bore andan integral forwardly projecting guide portion extending centrallywithin said stepped bore, said guide portion cooperating with said rearand supplemental heads to. form an annular valve chamber surrounding theguide portion within said larger bore, said supplemental head formingthe rear end wall of the valve chamber and the shoulder at the junctureof the alined bores providing the front end valve chamber wall, saidfront end wall providing an annular valve seat and said reduced boreconstituting means for connecting the front end of the valve chamberdirectly with the rear end of the motor cylinder, and a disc'valveguided for reciprocation on said guide portion and engageablealternately with the rear end valve chamber wall and the annular valveseat at the juncture of the alined bores, said valve when seated againstsaid annular valve seat cutting oiT communication of said reduced borewith the valve chamber.

ELMER G. GAR'I'IN.

